[webkit-gtk] FTL-JIT LLVM

Manuel Selva manuel.selva at inria.fr
Sun Nov 27 06:36:04 PST 2016

Hi Adrian, hi Michael,

Thank your for your quick answers.

We are looking for an LLVM based version to investigate parallelization 
opportunities using existing tools based on LLVM such as in the 
following research work:


Regarding your answers, I'll try to compile and run JavaScriptCore in 
the 2.11.2, 2.11.3 and 2.11.4 releases of WebKit and let you know.



On 26/11/2016 14:03, Adrian Perez de Castro wrote:
> On Fri, 25 Nov 2016 20:25:54 -0600, Michael Catanzaro <mcatanzaro at igalia.com> wrote:
>> On Fri, 2016-11-25 at 23:06 +0100, Manuel Selva wrote:
>>> 1- What is the last version of Webkit including a JavaScript engine
>>> with
>>> 4 tiers and based on LLVM ?
>> There was not actually ever any stable release that used LLVM. The LLVM
>> dependency was added during the 2.12 development cycle but removed
>> before the 2.12.0 release because the LLVM FTL backend was obsoleted by
>> the B3 (bare bones backend) earlier than we expected. B3 handles the
>> subset of LLVM intermediate representation needed by JavaScriptCore
>> much faster than LLVM can, as LLVM needs more features than
>> JavaScriptCore does. (I don't know more than this; you can ask the JSC
>> developers on webkit-dev@ if you're interested.)
> There's also a nice post in the WebKit blog about the B3 backend:
>   https://webkit.org/blog/5852/introducing-the-b3-jit-compiler/
> Michael is right, and you should use a released version of WebKitGTK+ (none
> of which need LLVM), unless you have a very strong reason to use one of the
> development snapshots. And even in that case, you would be probably in a
> better spot by making your code work with the most recent stable release
> because it contains significant improvements and security fixes.
> Regards,
> —Adrián

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